Twin motor battery charging

"ok, I have a 1976 slickcraft

"ok, I have a 1976 slickcraft 285 that has twin 233 mers in it. When I troll with only the port engine, all the electronics and everything electric on the boat is wired into the starboard motor battery, which after a couple hours of not running the starboard engine results in not enough juice in the starboard battery to turn that engine over to start it. The boat does have dual battery shutoffs with each switch being able to have 3/4 of a battery, 1 battery , or both batteries, My question is are these switches wired wrong which is preventing both batteries from being charged off one engine or is there a way to link both batteries so they do charge when just one engine is running so you can not end up with a dead battery?"

You can get a dual battery iso

You can get a dual battery isolator that takes the charge from one alternator and charges two batteries. It would need a on/off switch for the other engine not running so its own alternator will charge the battery and there won't be any cross talk interference between two alternators.

I myself would install the dual charge isolator to the starboard engine along w/a group 27 deep cycle battery for all the electronics and not worry about overworking an idling alternator; it isn't putting out much juice while trolling.

"Guy is quite correct. Its not

"Guy is quite correct. Its not a good idea to run electronics off of a "start" battery. This type of battery is designed to do just that, start an engine and then be recharged. "Deep Cycle" batteries are the ones designed to run loads for long periods of time between recharges."

"these are both deep cycle bat

"these are both deep cycle batteries, its not just the electronics that is wired into this engine, but everything 12 volt that is on the boat, what type and size of a dual battery isolator would I need"

"Isolator needed is based upon

"Isolator needed is based upon the alternator output. Below is 70 amp max. alt. output

http://www.marineengine.com/products/accessory.php?in=2901702"

"RE:"these are both deep c

"RE:"these are both deep cycle batteries, "

Deep cycle or start/deep cycle?"

FYI a deep cycle battery will

FYI a deep cycle battery will power 3 times longer than a starting battery but also takes three times longer to charge back up